Saddle pad question

[Marlene Moss <MARLENE.MOSS@WCOM.COM>]

I am riding with a Synergist saddle that fits my horse really well (been
checked by 2 saddle fit experts and I check regularly too).  The original
pad that it came with was getting worn and smashed and my mare is pretty
sensitive, so I thought I'd replace it with something a little thicker -
also on the advice of my saddle fitter/chiro/vet.

So I got a 2x woolback.  It's pretty big and bulky and I'm not sure how much
I really like it.  It really seems to make my horse sweat a LOT under the
saddle (and she barely sweats at all otherwise) and it's so bulky that I
have a hard time keeping it in a good position when I put the saddle on.
Over the last few weeks, I've noticed random white hairs coming in on my
horse's back.  They're not concentrated in any one area, but very evenly
scattered in the saddle area, both sides.  This mare does have a tendency to
get random white hairs (she's bay), but I've never seen this before.  Am I
correct in thinking that the saddle pad is causing the white hairs?  Am I
causing damage?  Should I go back to the original pad which is just a little
too flat?  I want to buy a good saddle pad, but I really don't have the
$200+ for all the new fancy ones and I can't decide which technology is
better anyhow.

Can someone please tell me if my suspicions make sense and point me in the
direction of a cheap alternative for this year.  I can save the bucks for
something next year if it's really warranted.  Or let me know if I'm an
idiot and need to be spending the bucks now.

Thanks,
Marlene